Insoluble fiber is one of the two types of dietary fiber. Unlike its counterpart, soluble fiber, the insoluble form does not break down as it passes through the digestive tract, so it helps bulk up stools and promotes regular bowel movements. This fiber is found in many types of plants, and a diet high in fiber — of both soluble and insoluble varieties — tends to lead to improved health in a variety of ways.
Most people associate insoluble fiber with regularity. This type of fiber tends to bunch up in the digestive tract, and because it is not broken down and stays in solid form, it helps produce solid, well-sized stools. It also helps the stool retain more water. Solid, larger stool moves through the intestines more easily, and the higher water content makes regular bowel movements less of a strain.
Some health professionals believe that insoluble fiber acts as a cleanser of the digestive tract. Because it remains solid and fibrous as it travels through the intestines, it acts like a brush or sponge. Stray particles within the intestines tend to clump together with the fiber and are more easily removed from the body with normal bowel movements.
Both types of fiber appear to help patients with obesity and high cholesterol. It may decrease the risk of diabetes, heart disease, and many problems of the intestines. Having fiber in the diet tends to make a person feel more full, so it is easier to control portion size. It has few if any calories, so it makes a good addition to most weight loss plans.
Many products are clearly labeled as a source of insoluble fiber. Products to look for include whole grains, nuts, bran fiber, and many vegetables like celery, zucchini, and beans. People should eat as much of the food as possible, as the skin of vegetables and the husk of grains are often the greatest sources.